An IP address is used to identify a node in an Internet protocol (IP protocol). The use of the IP address as a node identifier and a locator has a problem of data delivery, such as making impossible mobile communication, multi-homing, security or end-to-end connection. That is, in mobile communication, the IP address changes with mobility, resulting in also change of the node identifier, which is not changed, thus it is contradictory. In addition, in multi-homing, a packet can be sent out via an another ISP, even in the case of line down, however, a plurality of IP addresses are required to utilize a plurality of ISPs, resulting in address exhaustion. In addition, also in the case where a plurality of interfaces is connected to one node, because a different node identifier becomes necessary by each interface, it not only makes address management complicated but also exhausts addresses. Further, because the Internet is originally a network where many persons can participate, it becomes difficult to ensure communication security only by the IP protocol used.
On the other hand, sensor network technology has been developing in recent years. It is a technology, for example, to acquire a sensing data obtainable from a large quantity of compact-type wireless sensor nodes via a network, and utilize this information at a place apart through the network. Such a sensor includes one configured by a sensor for measuring a state quantity (temperature, pressure, location etc.) of a measurement object or variation (low temperature/high temperature, low pressure/high pressure etc.) of the state quantity; a controller for controlling the sensor; a wireless processing unit for performing communication with a local station BST; a power source for supplying a power to the sensor, controller and wireless processing unit; and an antenna for performing transmission and reception. Because the sensor is limited as for utilizable power and has a restriction against hardware capability or scale of mounted software, a network protocol tends to be restricted. Because the IP protocol has high processing load, in many cases, a unique network protocol is used by each sensor network without mounting the IP protocol on the sensor, therefore it makes impossible to perform end-to-end communication by the IP in some cases.
As a protocol alternative to the above IP protocol, there has been proposed a host identity protocol (HIP) (Non-Patent Literature 1: R. Moskowitz and P. Nikandar, “Host Identity Protocol (HIP) Architecture,” RFC 4423, IETF, May 2006. (http://www.ietf.org/rfc/rfc4423.txt)). The HIP uses a public key as the host identifier, and an IP address as the locator. This public key generates host identity tags (HIT) of 128 bits size, which identifies each other in establishing a data session, and is used in communication of a host. A host (called an initiator) requiring communication with other host (responder) acquires the public key of the responder from a DSN server for using to generate the HIT. In this protocol, all the nodes have a pair of the public key and a private key, and premise a computationally expensive cryptographic method.
In addition, there is also a new protocol based on LINA (Location Independent Network Architecture) called LIN6 (Location Independent Networking for IPv6); (Non-Patent Literature 2: M. Ishiyama, M. Kunishiki, K. Uehara, H. Esaki, and F. Teraoka, “LINA: A New Approach to Mobility Support in Wide Area Networks,” IEICE Transactions on Communications, Vol. E84-B, No. 8, pp. 2076-2086, August 2001). It is one for using an Ipv6 address-type exclusive identifier as a node identifier, where the node acquires the exclusive locator and a present locator mapping from a mapping agent scattered in the Internet. The node uses an identifier for session recognition and the present locator for data packet routing. Translation between the identifier and the present locator is performed in a network layer of a protocol stack. This protocol requires two mapping agents: that is, a DSN for storing an identifier-mobility agent address, and a mobility agent for storing the identifier—the present locator. The LIN6 is said to make it possible to attain migration-transparent communication, without giving the influence on the existing Ipv6, by utilization of the LINA.
Further, there is also LISP (Locator/ID Separation Protocol); (Non-Patent Literature 3: D. Farinacci, V. Fuller, and D. Oran, “Locator/ID Separation Protocol (LISP)”, IETF Internet-draft, January 2007. (http://www.ietf.org/internet-drafts/draft-farinacci-lisp-00.txt)). This protocol uses a local IP address as an end point identifier (EID), which is used also in local on-site routing. Packet routing is performed outside the local part, by using a routing locator (RLOC), which an approaching tunnel router obtains from an exit tunnel router at an object terminal. This protocol is one for focusing on reduction of routing table size, because of increase in packet tunneling overhead and diffusion of mapping information.